Washington City Canal buried beneath Constitution Avenue

The Washington City Canal, constructed in the early 19th century to connect Tiber Creek with the Potomac and Anacostia, fell into disuse and was gradually filled and covered in the late 19th century. Its former channel runs beneath what is now Constitution Avenue NW, and the National Archives Building occupies part of the filled canal route. Historical and archaeological records document canal remnants beneath present-day federal buildings along the Mall.